A currently foreseen development of communication in cellular networks involves numerous small autonomous devices, which transmit and receive only small amounts of data (or are polled for data) occasionally, e.g. once a week to once per minute. These devices may be sensors or actuators of different kinds, which communicate with application servers within or outside a cellular network. The application servers configure the devices and receive data from them. Hence, this type of communication is often referred to as machine-to-machine (M2M) communication and the devices may be denoted machine devices (MDs). In the 3GPP standardization such devices may be denoted Machine Type Communication devices (MTC devices). In the following, such autonomous device is denoted machine device (MD).
So far focus has been directed to MDs being directly connected to the cellular network via the radio interface of the cellular network. However, a scenario which is likely to be more prevalent is that MDs connect to the cellular network via a gateway. In such scenarios the gateway acts like a UE towards the cellular network while maintaining a local network, typically based on a short range radio technology towards the MDs. Such a local network, which in a sense extends the reach of the cellular network (to other radio technologies but not necessarily in terms of radio coverage), has been coined capillary network and the gateway connecting the capillary network to the cellular network is herein referred to as a capillary network gateway (CGW).
FIG. 1 illustrates such capillary network 1, comprising a number of MDs 21, 22, 23. The MDs 21, 22, 23 are communicating with the CGW 4 over a first air interface 3 typically implementing a short range radio technology. The CGW 4 is in turn communicating with a node of the cellular network 5 over a second air interface 6. An application server 8 is also illustrated.